Evolution Test #1

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What is Anthropology?

1.The study of humankind. 2.The study of all aspects of the human species, including our biology

What are the subfields of Anthropology?

Cultural anthropology

Archaeology

Linguistic anthropology

Biological anthropology

What is Biological (Physical) Anthropology?

It is the study of human biology within evolutionary framework.

Two principal areas of interest:

1. Biological variation

2.How modern species (including our own) came to exist

What is variation?

•Variation refers to differences between individuals within populations as well as between populations.

•Anthropologists are interested in variation in terms of both biology and culture.

Individuals in a population vary from one another

What is Evolution?

•Evolution is change in living organisms over time.

•Both cultural and biological evolution interest anthropologists.

Evolution is a fact…living organisms have changed in the past and continue to change today. There are forms of life living today that did not exist in the past and vice versa.

Some Subfields of Biological Anthropology

•Paleoanthropology - study of the human fossil record

•Human genetics - study of the human genome

•Primatology - study of nonhuman primates.

•Osteology - study of skeletons.

The scientific method:

a problem is identified, a hypothesis is stated, and the hypothesis is tested by collecting and analyzing data.

Facts:

verifiable truth

Hypothesis:

A testable explanation of observed facts

Testability

Scientific hypotheses must be testable and falsifiable

Theory

A set of hypotheses that explain a large body of concrete facts, have been tested repeatedly and that have not been rejected

What is natural selection?

Natural Selection is a SCIENTIFIC THEORY that explains how organisms are biologically transformed.

Survival of some individuals over others because they have specific characteristics that better their odds of survival and reproduction.

Inheritance

parents pass on their traits to their offspring genetically

Selection

some variants survive and reproduce more than others

Time

successful variations accumulate over many generations

Science and Religion

•Many people feel that evolution represents a threat to their religious beliefs and is incompatible with spirituality.

•Creationism, Intelligent Design, and the existence of God are not scientific hypotheses.

•Science cannot rule out the existence of a creator.

Misconceptions About Evolution

Natural selection is “just” a theory….. but you don’t get better than that in science.

There is a lot of contention about evolution…but not among scientists.

Evolution does not imply progression and has no end goal.

Evolution is a scientific concept and does not have to be incompatible with religion or belief in God.

Biological evolution

A change in the genetic structure of a population. Also refers to the appearance of a new species.

Natural selection

Mechanism for change favoring the survival and reproduction of some organisms over others because of their biological characteristics

Fixity of Species

The notion that species, once created, can never change; an idea diametrically opposed to theories of biological evolution.

The Scientific Revolution

Discovery of the new world challenged fundamental views about the planet.

Exposure to new plants and animals increased awareness of biological diversity.

Aristotle’s Worldview

This beautifully illustrated seventeenth-century map shows the earth at the center of the solar system.

Around it are 7 concentric circles depicting the orbits of the moon, sun, and the 5 planets that were known at the time.

Nicolaus Copernicus (1514)‏

Heliocentric theory: Earth and planets revolve around the sun

Galileo Galilei (1564-1642)‏

Used mathematics to confirm Copernicus’ ideas

Universe is dynamic, not static

Earth not a focal point

Keppler, Descartes and Newton (1600s)

established the laws of physics, motion and gravity.

John Baptiste Lamarck

John Baptiste Lamack was the first to attempt to explain how evolution happens.

Inheritance of
acquired
characteristics:

traits acquired during life passed on to offspring (Lamarck's ideas)

George Cuvier

introduced the concept of extinction and the theory of catastrophism

Catastrophism

The view that the earth’s geological landscape is the result of violent cataclysmic events.

Old species have become extinct through these cataclysmic events and are replaced with newly created species.

Cuvier promoted this view, especially in opposition to Lamarck.

Charles Lyell

Geologist

Uniformitarianism

Immensity of geologic time

Uniformitarianism

The theory that the earth’s features are the result of long term processes that continue to operate in the present as they did in the past.

Elaborated on by Lyell, this theory opposed catastrophism and contributed strongly to the concept of immense geological time.

Thomas Malthus

Economist

Interested in factors causing population increase and decrease.

Populations increase exponentially while food supplies stay the same.

Always more people born than can survive on the available resources.

Results in a struggle for survival.

Mary Anning

Discovered the first complete fossil of Ichthyosaurus, a large fishlike marine reptile.

She became known as one of the world’s leading “fossilists” and contributed to the understanding of the evolution of marine life over 200 million years ago.

Processes of Natural Selection

Species can produce offspring at a faster rate than food supplies increase.

There is biological variation within all species.

In each generation, more individuals are produced than can survive.

Processes of Natural Selection (continued)

Individuals that possess favorable traits or variations are more likely to survive and produce offspring.

Environmental context determines whether a trait is beneficial.

Traits are inherited and passed on to the next generation.

Processes of Natural Selection #3

Variations accumulate over long periods of time, so later generations may be distinct from ancestral ones.

As populations respond to pressures over time, they may become distinct species, descended from a common ancestor.

Alfred Russell Wallace (1823-1913)‏

Independently developed theory of Natural Selection

A naturalist who worked in South America and Southeast Asia.

Suggested species descended from other species and new species were influenced by environmental factors.

Presented paper on evolution and natural selection to the Linnean Society of London jointly with Darwin.

The Cell

Basic unit of life

Prokaryotic cells = single celled organisms

–appeared 3.7 bya

Eukaryotic cells

–Have nucleus

–appeared 1.2bya (possibly even 3bya)

Human body has 1,000 billion (1,000,000,000,000) cells

Structure of a Eukaryotic Cell

Cell membrane

Organelles

Ribosomes-manufacture proteins

Mitochondria-generate cell’s energy

Nucleus

DNA & RNA (genetic material)

2 Types of Eukaryotic Cells

Somatic - body tissues

Gametes - sex cells

–Ovum (egg)‏

–Sperm

–Zygote - union between a sperm and an ovum.

DNA: The Genetic Code

DNA molecule provides:

Codes for the building of biological structures

The means to translate this code.

Information for operating, maintaining and repairing organisms.

DNA Structure

DNA: 2 strands arranged in a double helix held by chemical bases.

Sugar-Phosphate strands held together by nitrogen bases

Nucleotide: Sugar molecule (deoxyribose), phosphate unit and base

4 DNA Bases

Adenine

Thymine

Cytosine

Guanine

A only binds with T

C only binds with G

The bases provide the instructions for the structures and functions

in your body.

RNA

RNA differs from DNA in three important ways:

1.It’s usually single-stranded. (This is true of the forms we discuss, but it’s not true for all.)‏

2.It contains a different type of sugar. (Ribose instead of Deoxyribose)‏It contains the base uracil as a substitute for the DNA base thymine. (Uracil (U) is attracted to Adenine (A) , just as Thymine (T) is.)

The study of the frequency of alleles, genotypes, and phenotypes in populations.

Microevolution:

changes in the frequency of alleles from one generation to the next.

Macroevolution

the change from one species to another.

Steps in population genetics

1.Measure the allele and genotype frequencies in our population for a specific trait.

Ex: figure out the frequencies of the genes for eye color B and b.

2.Figure out what these same frequencies should look like if the population is NOT evolving.

3.Compare the actual frequencies with the hypothetical ones.

If the numbers are the same the population is not evolving at this gene.

Steps in population genetics (continuation)

Measure the allele and genotype frequencies in our population for a specific trait.

Ex: figure out the frequencies of the genes for eye color B and b.

Figure out what these same frequencies should look like if the population is NOT evolving.

Compare the actual frequencies with the hypothetical ones.

If the numbers are the same the population is not evolving at this gene.

Genotype Frequency:

•Measure of the relative proportions of different genotypes

•# of individuals with each genotype divided by total # of individuals

•People with Bb: 50

•People in the population: 100

•Genotypic frequency of Bb: .5 or 50%

Phenotype Frequency:

•Measure of the relative proportions of different phenotypes

•# of individuals with each phenotype divided by total # of individuals

•People with Blue eyes: 50

•People in the population: 100

•Phenotypic frequency of Blue eye: .5 or 50%

Allele Frequency:

•Relative proportions of different alleles

•# of each allele divided by the total # of alleles

•B alleles in the population: 50

•People in the population: 100

•Total alleles in the population: 200

•Allele frequency for B: .25 or 25%

Evolution occurs when gene frequencies change

In the absence of evolutionary forces, allele frequencies will remain constant over time

The Population will be in Equilibrium

A population may be in equilibrium for a certain gene but will never be in complete equilibrium for all of its genes.

Hardy-Weinberg Principle

G. Hardy and W. Weinberg proposed that the frequency of alleles and genotypes in a population will remain constant if the population is in genetic equilibrium.

Hardy-Weinberg Principle

Five conditions are required in order for a population to remain at eqiulibrium.

1.Large population (i.e. no genetic drift)

2.Random mating

3.No mutation

4.No gene flow

5.No natural Selection

Large Population

A large breeding population helps to ensure that chance alone does not disrupt genetic equilibrium. In a small population, only a few copies of a certain allele may exist.

2. Random Mating

In assortative (non-random) mating, individuals tend to choose mates similar to themselves.Results in fewer heterozygous individuals than you would expect in a population where mating is random

3. No Mutation

Any mutation in a particular gene would change the balance of alleles in the gene pool.

4. No Gene Flow

For the allelic frequency to remain constant in a population at equilibrium, no new alleles can come into the population, and no alleles can be lost. Both immigration and emigration can alter allelic frequency

5. No Natural Selection

If selection occurs, those alleles that are selected for will become more common.

§For example, if a weed is resistant to herbicide, the allele for resistance may become more frequent in the population.

Hardy-Weinberg Equation

The mathematical equation expressing the predicted frequencies of alleles in a population if that population is in equilibrium.

Provides a tool to establish whether allele frequencies in a human population are changing.